Risk of Plasmodium falciparum infection in south-west Burkina Faso: potential impact of expanding eligibility for seasonal malaria chemoprevention

Abstract

Burkina Faso has one of the highest malaria burdens in sub-Saharan Africa despite the mass deployment of insecticide-treated nets (ITNs) and use of seasonal malaria chemoprevention (SMC) in children aged up to 5 years. Identification of risk factors for Plasmodium falciparum infection in rural Burkina Faso could help to identify and target malaria control measures. A cross-sectional survey of 1,199 children and adults was conducted during the peak malaria transmission season in the Cascades Region of south-west Burkina Faso in 2017. Logistic regression was used to identify risk factors for microscopically confirmed P. falciparum infection. A malaria transmission dynamic model was used to determine the impact on malaria cases averted of administering SMC to children aged 5-15 year old. P. falciparum prevalence was 32.8% in the study population. Children aged 5 to < 10 years old were at 3.74 times the odds (95% CI = 2.68-5.22, P < 0.001) and children aged 10 to 15 years old at 3.14 times the odds (95% CI = 1.20-8.21, P = 0.02) of P. falciparum infection compared to children aged less than 5 years old. Administration of SMC to children aged up to 10 years is predicted to avert an additional 57 malaria cases per 1000 population per year (9.4% reduction) and administration to children aged up to 15 years would avert an additional 89 malaria cases per 1000 population per year (14.6% reduction) in the Cascades Region, assuming current coverage of pyrethroid-piperonyl butoxide ITNs. Malaria infections were high in all age strata, although highest in children aged 5 to 15 years, despite roll out of core malaria control interventions. Given the burden of infection in school-age children, extension of the eligibility criteria for SMC could help reduce the burden of malaria in Burkina Faso and other countries in the region.

Figure 1

Map of the 10 study villages: (A) location of Burkina Faso, (B) location of Cascades Region in Burkina Faso and (C) location of Banfora Health District and study villages in Cascades Region. The map was generated using QGIS 3.16. Background layers were downloaded for OpenStreetMap, villages were digitised by the authors using GPS coordinates collected in the field using a GARMIN eTREX 10 GPS.

Figure 2

Prevalence of P. falciparum infection by age group in study population. Error bars are 95% confidence intervals.

Figure 3

Clinical incidence of malaria predicted by either halting or extending the age range of the annual SMC campaign. Model predictions for the average number of clinical cases per year per 1000 people if SMC was halted (red bar), continued implementation across the existing target age (0–5 years, blue bar) or extended to 0–10 years old (green bar) or 0–15 years (purple bar). Incidence is averaged over the whole population (all ages) over a three-year period following the change in policy to reflect the regularity of mass ITN campaigns. ITNs are assumed to be either pyrethroid-only ITNs (left bars) or pyrethroid- piperonyl butoxide (PBO) ITNs (right bars).